Python中的空类对象 [英] Empty class object in Python

问题描述

我正在教授有关面向对象程序设计的Python类，并且在我学习如何解释类​​时，我看到了一个空的类定义:

I'm teaching a Python class on object-oriented programming and as I'm brushing up on how to explain classes, I saw an empty class definition:

class Employee:
    pass

然后，该示例继续为此类的对象定义名称和其他属性:

The example then goes on to define a name and other attributes for an object of this class:

john = Employee()
john.full_name = "john doe"

有趣！

我想知道是否有一种方法可以为此类实例动态定义函数?像这样:

I'm wondering if there's a way to dynamically define a function for an instance of a class like this? something like:

john.greet() = print 'Hello, World!'

这在我的Python解释器中不起作用，但是还有另一种方法吗?

This doesn't work in my Python interpreter, but is there another way of doing it?

推荐答案

一个类或多或少是对象的属性dict的精美包装.当实例化一个类时，您可以为其分配属性，这些属性将存储在foo.__dict__中.同样，您可以在foo.__dict__中查找您已经编写的所有属性.

A class is more or less a fancy wrapper for a dict of attributes to objects. When you instantiate a class you can assign to its attributes, and those will be stored in foo.__dict__; likewise, you can look in foo.__dict__ for any attributes you have already written.

这意味着您可以执行一些巧妙的动态操作，例如:

This means you can do some neat dynamic things like:

class Employee: pass
def foo(self): pass
Employee.foo = foo

，以及分配给特定实例. (添加了self参数)

as well as assigning to a particular instance. ( added self parameter)

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